Add PmPowerPolicy to simplify implementation of power policies

In the future, this may also be useful if any classes outside of power policies need to access the PowerManager instance.

src/power_policy/_power_policy.hpp

@@ -1,8 +1,10 @@
 #pragma once
 
 #include <memory>
+#include <power_manager.hpp>
 #include <process.hpp>
 
+// forward declaration to avoid circular dependency between PowerPolicy and Window
 class Window;
 
 /**
@@ -39,3 +41,13 @@ class PowerPolicy
      */
     static std::unique_ptr<PowerPolicy> setup_power_policy(const std::string &policy_str);
 };
+
+/**
+ * Subclass of PowerPolicy, which is extended by power policy implementations
+ * which use PowerManager. In the rest of the codebase, you should accept
+ * the more general PowerPolicy interface instead of this one.
+ */
+class PmPowerPolicy : public PowerPolicy {
+protected:
+    PowerManager pm{};
+};

src/power_policy/high.hpp

@@ -3,11 +3,8 @@
 #include "_power_policy.hpp"
 #include "power_manager.hpp"
 
-class PowerPolicy_FixedHigh : public PowerPolicy
+class PowerPolicy_FixedHigh : public PmPowerPolicy
 {
-private:
-    PowerManager pm{};
-
 public:
     PowerPolicy_FixedHigh()
     {

src/power_policy/imx8_alternating.hpp

@@ -8,10 +8,9 @@
  *
  * NOTE: this is a test power policy, the error messages are not very helpful
  */
-class PowerPolicy_Imx8_Alternating : public PowerPolicy
+class PowerPolicy_Imx8_Alternating : public PmPowerPolicy
 {
 private:
-    PowerManager pm{};
     CpufreqPolicy &a53_pol = pm.get_policy("policy0");
     CpufreqPolicy &a72_pol = pm.get_policy("policy4");
     CpuFrequencyHz f1_a53 = 0;

src/power_policy/imx8_fixed.hpp

@@ -9,11 +9,8 @@
  *
  * NOTE: this is a test power policy, the error messages are not very helpful
  */
-class PowerPolicy_Imx8_Fixed : public PowerPolicy
+class PowerPolicy_Imx8_Fixed : public PmPowerPolicy
 {
-private:
-    PowerManager pm{};
-
 public:
     /** *_freq_i - integer, range <0,3> */
     PowerPolicy_Imx8_Fixed(const std::string& a53_freq_i, const std::string& a72_freq_i)

src/power_policy/imx8_per_process.hpp

@@ -9,10 +9,9 @@
  *
  * NOTE: this is a test power policy, the error messages are not very helpful
  */
-class PowerPolicy_Imx8_PerProcess : public PowerPolicy
+class PowerPolicy_Imx8_PerProcess : public PmPowerPolicy
 {
 private:
-    PowerManager pm{};
     CpufreqPolicy &a53_pol;
     CpufreqPolicy &a72_pol;
     const cpu_set a53_cpus{0b001111};

src/power_policy/low.hpp

@@ -3,11 +3,8 @@
 #include "_power_policy.hpp"
 #include "power_manager.hpp"
 
-class PowerPolicy_FixedLow : public PowerPolicy
+class PowerPolicy_FixedLow : public PmPowerPolicy
 {
-private:
-    PowerManager pm{};
-
 public:
     PowerPolicy_FixedLow()
     {

src/power_policy/minbe.hpp

@@ -3,11 +3,8 @@
 #include "_power_policy.hpp"
 #include "power_manager.hpp"
 
-class PowerPolicy_MinBE : public PowerPolicy
+class PowerPolicy_MinBE : public PmPowerPolicy
 {
-private:
-    PowerManager pm{};
-
 public:
     PowerPolicy_MinBE()
     {